SKA-low and the Aperture Array Verification System

Transcription

1 SKA-low and the Aperture Array Verification System Randall Wayth AADCC Project Scientist On behalf of the Aperture Array Design & Construction Consortium (AADCC)

2 AADCC partners ASTRON (Netherlands) ICRAR/Curtin University (Aus) INAF (Italy) University of Oxford (UK) University of Cambridge (UK) KLAASA (China) Associates: Jive University of Manchester University of Malta Large, international effort. ~$50M budget to pre-construction Acknowledgements: CSIRO, Pawsey Supercomputing Centre 2 2

3 SKA-low: end-to-end Signal & Data Transport Mase r Low frequency Aperture Array Central Signal processor Scienti sts! Telescope Manager M&C AADC Responsibili ty HPC HPC HPC Courtesy: Jan Geralt bij de Vaate Bulk Store Infrastruct ure HPC UV Processor Bufer store Switch Correlator Beamforme r Bufer store Switch Beamforming PowerCooling Science Data processor

4 SKA1-Low: Aperture Array Verification Systems Task: Demonstrate LFAA functionality/performance of baseline design through accurate, in-situ measurement i.e. can we show that LFAA designs meet requirements? Solution: use an existing radio telescope (MWA) and well-known properties of radio sky for: absolute measurements of array sensitivity (A/T) and beam pattern A. Sutinjo et. al., Characterization of Aperture Array Verification System 0.5: Radio Astronomy Interferometry and Full Wave Simulation. IEEE TAP submitted T. Colegate et. al., Antenna array characterization via radio interferometry observation of astronomical sources, IEEE CAMA, 2014 P. Hall et. al., First results from AAVS 0.5: A prototype array for next generation radio astronomy, ICEAA, 2013` 4 4

5 Aperture Array Verification System log-periodic SKALA antennas as a beamformed tile MHz deployed near SKA1-Low site under the MWA external instrument policy 5 5

6 Aperture Array Verification System

7 For measurement: swap 1 MWA tile with AAVS

8 Measured and simulated sensitivity (A/T) for three calibrators and pointings Hydra A Az=0, El=75.4 3C444, Az=0, El=81.3 Hercules A, Az=0, El=58.3 Note: simulations include measured T SKA-low AAVS. OzSKA RX 8 8

9 AAVS 0.5 beam pattern at 220 MHz: Xpolarization Hydra A & MWA AAVS 0.5 AAVS 0.5: Az=0, ZA=14.6 Earth rotation: source passes through AAVS 0.5 beam MWA tiles track source 9 9

10 Antenna array characterization - summary Demonstrated measurement and simulation tools to test array performance characteristics Our simulations generally show good agreement with measurement, but we must ensure: simulations accurately represent the observation (soil, sky, beam pointing) measurements are accurate (correct calibration!) These measurements were an important contribution to the Square Kilometre Array preliminary design review AAVS 0.5 results, extrapolated to full-sized telescope, meet current specifications 10 10

11 AAVS0.5 RFoF tests 2015 March RF over fibre (RFoF) test system for a single polarisation on AAVS0.5 test tile Perform same A/T test as previous, compare results 11

12 AAVS0.5 RFoF A/T results 12 12

13 Timeline and recent history History 2012: initial antenna design/lna testing in UK 2013+: installation of AAVS0.5 at MRO, connection to MWA 2014: development of prototype RF, receiver & digital gear by AADCC members 2015: successful PDR with special mention for prototyping & verification 13 13

14 Timeline and recent history History 2012: antenna design/lna testing in UK 2013+: installation of AAVS0.5 at MRO, connection to MWA 2014: development of prototype RF, receiver & digital gear by AADCC members 2015: successful PDR with special mention for prototyping & verification Future: Aperture Array Verification System #1 (AAVS1) Q1 2015: new LNAs, receivers, digital systems delivered Q3 2015: initial UK-based testing of ant->receiver->digital systems Q4 2015: conformance testing & delivery to MRO 2016: AAVS1, installation at MRO, integration with MWA 14 14

15 LFAA Signal Chain Antenna & LNA Receiver Signal Processing RFoF o/e ADC Antenna structure Antenna Processing Facility e/o Network e/o Spectral flters LNA Part Station beamformi ng Tile Beamformin g Tile Processing module, TPM Data out

16 Aperture Array Verification System #1 (AAVS1) Goal: Full-sized SKA station to properly test against requirements Current thinking: Will use all proposed LFAA technology from antennas through to digital beamformer, including RF over fibre Essential prototyping & development, but maximal re-use of MWA infrastructure & systems Successful test will retire large amount of technical risk 1 x 256 antenna station; 3 x 48 antenna stations 35 m diameter stations (at least for 256 antenna station) Baseline lengths m Aim to use similar interferometric methods Much of the testing of array performance can be done via cross-correlation with MWA tiles ( MHz) 16 16

17 AAVS 1 representative locations 17 17

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19 RF fibre path to MRO control 19 19

20 Summary Aperture Array Design & Construction Consortium is making solid progress in development and verification during pre-construction. Aus involvement in AADCC is a comprehensive and essential part of the Aus SKA effort Test and verification systems are an essential part of SKAlow; On-the-ground prototyping avoids nasty surprises later. AAVS0.5 utilises MWA collecting area, signal chain, M&C & data processing expertise AAVS0.5 system has demonstrated A/T meets spec at specified freqs Beam model verification via drift scans of strong sources AAVS1 system to be deployed late 2015, again with focus on integration with MWA for mutual benefit

21 Science with AAVS1 AAVS1 = full SKA-low station = substantial collecting area (~1 150 MHz = ~2700 Jy SEFD) 35m single dish Improved MWA calibration (collecting area, FoV) Hybrid array imaging/calibration Low freq flux scale (with calibrated element) EoR PS with hybrid arrays 21 21